750's work for the majority of contractors around here. Never had a request for anything bigger.
We also have a 950 that we rent (usually kept on a cart), as well as a couple larger Stihls that we sell (TS460 and another I can't remember).
We do not have a ring saw, though I'd like to get one. What we do have is a K650 cut-n-break. We just recently picked it up for our rental line, and have only rented it out, maybe 5 times, but it has gotten rave reviews. 16" cutting depth FTW.